Vol. 8, 1922 
BIOLOGY: A. P. DACHNOWSKI 
225 
which the numerous and varied animal types can be made to fall into any 
evolutionary plan is to consider the radially symmetrical colonial coelenter- 
ates as representing the highest degree of purely biological perfection, and 
all other animals (except the sponges which are their equivalent) as derived 
from them through the appearance of various defects which had the an- 
omalous result of leading to increased bodily efficiency. 
THE CORRELATION OF TIME UNITS AND CLIMATIC CHANGES 
IN PEAT DEPOSITS OF THE UNITED STATES AND EUROPE 
By Ai^ifRKD P. Dachnowski 
U. S. Dept. of AgricuIvTure, Washington, D. C. 
Read before the Academy April 25, 1922 
This paper is a continuation of a previous publication'' which con- 
tained a discussion of the evidence in peat deposits of the United States 
regarding climatic changes since the last Ice age. 
For purposes of comparison a brief account in tabular form is presented 
to show certain correlations between peat deposits in this country with those 
of the continent of Europe. 
1. A correlation of American with European glacial drift sheets has been 
made by Leverett.^ By considering with Leverett the early and late 
Wisconsin Glaciation contemporaneous with the Wiirm glaciation it is 
possible to correlate the corresponding minor glacial stages. 
The three readvances of the ice sheet that produced the morainic systems 
of the late Wisconsin : the Valparaiso-Kalamazoo, Lake Border, and Port 
Huron may be regarded as corresponding to Penck and Briickner's^^ 
cycle of mountain glaciations of the Alps : the Buhl, Gschnitz, and Daun- 
stadia — and to those of the Scandinavian continental ice-fields : DeGeer's'" 
Dani-, Goti-, and Fini-glacial stadia. 
2. The Strati graphic Study of Peat Deposits in the United States has fur- 
nished valuable data as to the botanical composition of types of peat and 
their economic value. It has been shown also that the material formed 
under wet conditions differs in botanical composition and texture from 
that formed during dry periods, and that the study of separate and distinct 
layers in deposits formed within the main morainic systems during the 
glacial retreat serves to throw much light on the character of the past 
climatic changes. 
Evidence is now presented by means of the position of conspicuous lay- 
ers of forest peat, fibrous sedge and reed peat, and colloidal peat, to show the 
equivalence of peat deposits which were formed in the respective morainal 
belts of the United States and Europe. The greater structural complexity, 
it will be noted, is confined to areas within the oldest of the morainic 
